In order to enhance or modify the chemical and/or physical characteristics of certain pesticides, certain materials are added to form a mixture for spraying. Generally referred to as adjuvants, these materials have no pesticidal activity of their own. Since spray application can be critical to the performance of the agricultural chemical, adjuvants are added to reduce application problems such as chemical stability, incompatibility, solubility, suspension, foaming, drift, evaporation, volatilization, phytotoxicity, surface tension, droplet size and coverage. They can, depending on their type, enhance wetting, spreading, sticking, emulsifying, dispersing and biological activity. Adjuvants include wetting agents, crop oil concentrates, spreaders, stickers, buffering agents, foaming and anti-foaming agents, dispersing agents and drift control agents. Over 200 EPA-registered pesticides have specific recommendations on their labels for adjuvant use. These are recommended for one of two reasons--or both. First, to enhance biological activity of the pesticide and second, to reduce, minimize or eliminate spray application problems as noted previously. There are several different types of adjuvants recommended. To achieve consistent, effective results from them, the user must first select the desired type of adjuvant and then the appropriate product within that specific type for use with a particular pesticide and then use that product at recommended rates.
It is known that petroleum hydrocarbon spray oils increase the efficacy of herbicides, fungicides and other pesticides by enhancing the deposition characteristics and wetting and spreading of the spray solution resulting in a more even and uniform spray deposit or by increasing the biological effect of certain pesticides. Such spray oils can increase penetration and slow evaporation. Paraffin based spray oil is a petroleum oil used as dormant spray, summer oil, carrier for pesticides or an adjuvant to increase the efficacy of agricultural chemicals.
In U.S. Pat. No. 3,977,322, an agricultural spray oil composition comprising a major amount of a petroleum oil and a minor amount of a vegetable oil is disclosed as providing a particularly improved carrier which enhances the effectiveness of selective herbicides. These compositions also include ionic and nonionic surfactants such as fatty acid amides of alkanol amines and alkyl substituted phosphoric acids.
A synergistic herbicidal composition is disclosed in U.S. Pat. No. 4,755,207 and comprises a non-phytotoxic crop oil, a surfactant, and hydrophobic mycoherbicide spore. The oils are once refined vegetable oils or highly refined paraffinic material. The surfactant can be anionic, cationic or nonionic.
Some applications require the separate addition of buffering agents to adjust the pH of alkaline waters used to make up the spray solutions. The buffering agents regulate solution pH to avoid hydrolysis of pesticides that tend to decompose in alkaline spray solutions. Generally, the spray's Ph should be adjusted to a range of 4 to 6 or slightly acidic. Known buffering agents include alkyl aryl polyethoxy ethanol phosphates and organic phosphatic acids as the principal functioning agents. Typically, such a buffering agent is added to the water which is then combined with the pesticide and any other adjuvants required.
U.S. Pat. No. 4,244,049 relates to aqueous-lower alkanol solutions containing alkylaryl polyoxyethylene glycol phosphate esters which act as compatibility agents for mixtures of liquid fertilizer and pesticides. The solution contains about 20% methanol, about 16% water and about 64% of the phosphate ester.
A biocidal fine powder and an agricultural suspension containing the fine powder and an adjuvant are disclosed in U.S. Pat. No. 4,851,421. The adjuvant can be a polyoxyalkylene-type nonionic surface active agent or polyoxyalkylene alkyl or alkylaryl ether phosphates or their salts. The composition does not include any oil components.
It is advantageous to reduce the separate addition of each of the adjuvants to the herbicide or pesticide to save time and to reduce possibility of error in the amounts added since mixing is typically done in the field by unskilled workers. However, the components of an adjuvant composition must form a homogeneous liquid mixture, not a slurry or suspension. Otherwise, the amount of oil and surfactant in the spray will vary form use to use and these variations would adversely affect the physical properties of the spray. In the prior compositions, adjuvants such as buffering agents have been added to the water, then combined with the other adjuvants and the active ingredient because the phosphate compounds used as buffering agents are hydrophilic polar compounds. It is difficult to combine such compounds with oil and obtain a homogeneous composition having the desired spray uniformity and coverage.
It is the object of this invention to provide an essentially non-aqueous, single-phase adjuvant composition containing oil plus surfactant blend and which provides buffering capability. Even after the addition of alkaline water and pesticides, use of this composition reduces and/or maintains the pH of the spray mixture within a desired range to prevent hydrolysis of the pesticide.